The JavaScript EncodeAs Burp Plugin allows you to encode strings in the JavaScript format (i.e. Unicode/Hex), similar to Burp's Convert-To but specifically for within JSON/JavaScript. Can be useful ...

Learn how to use encoding and escaping techniques in HTML, JavaScript, URL, and CSS output to prevent XSS attacks on your web applications.

So this would mean adding new text areas for HTML and JavaScript in both the Encode and Decode tabs. It might be worth increasing the default dialog size a bit, but see what it looks like. The ...